Glow discharge tube



Feb. 19, 1957 H. J. GEISLER GLOW DISCHARGE TUBE 2 Sheets-Sheet 1 FiledMay 22, 1952 FIG. 2

SUSTAINING VOLTAGE \COMPLETE ISOLATION NO ISOLATION ANODE CURRENT INMILLIAMPERS I ai INVENTOR HELMUT J. GEISLER ATTORNEY :I'II:

FIG. 3

Feb. 19, 1957 H. J. GEISLER 2,782,343

GLOW DISCHARGE TUBE Filed May 22., 1952 2 Sheets-Sheet 2 COATED COATEDFIG. 5a

0 OUTPUT INVENTOR HELMUT J. GEISLER E '5 BYE} ATTORNEY a United StatesPatent 2,782,343 GLOW DISCHARGE TUBE Helmut J. Geisler, WappingersFalls, N. Y., assign-or to Interuauonal Business Machines Corporation,New York, N. Y., a corporation of New York Application May 22, 1952,Serial No. 289,304

2 Claims. (Cl. 315-169) This invention relates to gaseous dischargetubes and more particularly to switches or triggers of the gaseous glowdischarge type.

Such tubes are generally of two types, both employ two cathodes and asingle anode common thereto. One type employs intermediate or glowtransfer means be! tween the two cathodes of the tube to provide a fastand positive glow transfer from each cathode to the other. The othertype 'tube employs no internal coupling between the cathodes and dependsupon external cir-.

A further object is to provide a trigger tube having two cathodes and asingle anode whereinthe voltage drop between the anode and each cathodeis of a diiferent value because of the inherent structure of thecathodes.

A still further object is to provide a novel cold cathode switch-triggertube wherein one input pulse must be applied to produce an auxiliaryglow discharge and a second input pulse must be applied to a secondinput to produce a main glow discharge which provides an output.

Other objects of the invention will be pointed out in the followingdescription and claims and illustrated in the accompanying drawings,which disclose, by way of examples, the principle of the invention andthe best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 is a diagrammatic showing of a gaseous discharge trigger tube,

Fig. 2 shows characteristic curves representing the operation of agaseous discharge trigged tube under different conditions of ionicmigration,

Fig. 3 shows one embodiment of the trigger tube of the invention,

Fig. 4 shows another embodiment of the trigger tube of the invention.

Fig. 5 shows diagrammatically a further embodiment of the trigger tubeof the invention,

Fig. 5a shows a variation of the embodiment shown in Fig. 5; and

Fig. 6 shows an embodiment of the switch-trigger tube of the invention.

Briefly, one embodiment of the gaseous trigger tube of the inventionincludes two cathodes and a single anode functionally common to andlocated intermediate the two cathodes. Triggering action is obtained byapplying input pulses to the cathodes or the anode. In operation theglow discharge can exist between the anode and only one cathode. Eachinput pulse causes the glow discharge to be transferred to exist betweenthe anode and the other cathode. The anode is in the form of either aplate having one or more holes connecting its planar faces or a screenwire. The holes through the plate or between the wires of the screenwire, as the case may be, provided for preselected ionic migration orleakage there through from the vicinity of the cathode to which the glowdischarge exists to the vicinity of the other cathode. In this mannerthe breakdown voltage of the gaseous atmosphere in the vicinity of thelatter cathode is lowered and a more positive glow transfer thereto isaccordingly facilitated.

The switch-trigger tube of the'invention provides a first cathode whicheifectively divides the tube envelope into two ionic compartments. Aninput pulse is applied to a first starter anode to establish a glowdischarge between that anode and the first cathode. During the existenceof this discharge ionic leakage occursinto the other compartment tolower the breakdown voltage thereis necessary that a glow dischargeexist between the first cathode and the first starter anode before thesecond input pulse can be employed to establish a glow discharge betweenthe main anode and main cathode.

Referring more particularly to Fig. l the gaseous discharge tubeincludes cathodes 10C and 11C and anode A, intermediate the cathodes.All electrodes are enclosed within the envelope 12 filled with anysuitable gaseous atmosphere. Cathodes 10C and are connected to groundthrough resistors 13 and 14 respectively. Anode A is connected throughresistor 15 to a suitable source of positive voltage designated B+. Ifthe resistor 15 is of sutficiently high value it will permit a steadyglow discharge from the anode A to either of the cathodes 10C and 11Cbut will not permit a glow discharge between the anode and bothcathodes. In operation then a glow exists initially in a state of stabledischarge between the anode and one cathode, called the fired cathode.If an appropriate positive pulse is applied to this fired cathode theglow discharge will be transferred to exist in a state of stabledischarge between the anode and other cathode. This glow transfer mayalso be accomplished by applying an appropriate negative pulse to theunfired cathode or to the anode. Obviously, if negative pulses areapplied to the anode to effect glow transfer a binary output is presentat the cathodes.

Fig. 2 shows a group of characteristic curves illustrating the operationof the tube of Fig. 1. If each fired gap is completely isolated from theunfired gap, for example, if the anode A is a solid metallic sheet, thebreakdown voltage of the unfired gap is substantially independent of thecurrent flowing in the fired gap as indicated by the complete isolationcurve. If no isolation is efiected between the cathodes; i. e., ions arepermitted to migrate freely in the entire envelope 12, the no isolationcurves approaches the sustaining voltage curve when appreciable anodecurrent flows. It is seen from inspection of the sustaining voltagecurve that the operating current value should be sufliciently large toavoid operating at the negative voltage characteristic of the curve.Such operation might produce self-oscillations or spurious glowtransfer.

It is seen that ideal tube operation would be along a curve such as thecurve C intermediate the no isolation and complete isolation curve. Toobtain such operation it is necessary to control the ionic leakage ormigration from the fired gap to the vicinity of the unfired gap.

Referring to Fig. 3 the novel glow transfer trigger tube 16 includeswire cathodes 17 and 18 each having an inwardly extending portion alongtheir length which portions extend toward a wire mesh anode 19. Thecathodes and anode are held in spaced relation by the upper and lowerspacers 2t} and 21,.respectively. In operation the tube may be connectedin circuit as shown. The terminals 22 and 23 connected to the cathodes17 and 18, respectivcly, and the terminal 24 connected to the anode 19may be employed as input and output terminals.

if a glow discharge exists between the anode 19 and the cathode 17 and apositive pulse is applied to terminal 22 or a negative pulse is appliedto terminal 23 or 24 the glow discharge will transfer to exist in astate of stable discharge between the anode 19 and the cathode 18.Accordingly, the voltage at the cathode 17 will decrease and the voltageat the cathode 13 will increase. If a positive pulse is now applied tothe terminal 23 or a negative pulse is applied to the terminal 22 or 24the glow discharge will be transferred to exist in a state of stabledischarge between the anode 19 and the cathode 17. Because the U-shaped,or inwardly extending portions of the cathodes, are nearest the anodethe glow discharge is confined to those portions and does not extend toother parts of the cathode wires.

When glow discharge exists from the anode to one cathode ions migratefrom the vicinity of that glow discharge through the screen wire anodeinto the vicinity of the other cathode or into the unfired gap. Suchmigration lowers the breakdown voltage of the unfired gap so thatgreater speed of glow transfer is possible as well as the use of inputpulses of less amplitude. Operation is effected in accordance with thecurve C of Fig. 2.

Referring to Fig. 4 the tube 30 includes the wire cathodes 31 and 32 andan anode 33 intermediate the cathodes. The cathodes and anode are heldin a preselected spaced relation by the upper and lower spacers 34 and35 respectively. The anode 33 is formed as a flat sheet and has a holetherethrough as shown to permit ion migration from the tired gap intothe unfired gap to permit operation as indicated by curve C of Fig. 2.The number and size of the holes used will vary in accordance with theoperating requirements, the electrode spacing and the pressure of thegaseous atmosphere within the envelope of the tube.

Referring to Fig. the cathodes 4t] and 41 are of the wire type. Thecathode 40 has a relatively small and uncoatcd surface area as comparedto the surface area of cathode 41 which is coated with any suitablematerial such as activated barium-strontium compounds. The object inmaking the area of cathode 41 large relative to that of cathode 4t andof coating cathode 41 is to provide a voltage drop between the anode 33and cathode 41 which is less than the voltage drop between the cathode40 and anode 33 when a glow discharge exists across those respectivegaps and the values of resistors 13 and 14 are equal.

Since the voltage drop is less across a glow discharge between thecathode 41 and anode 33 than between the cathode 40 and anode 33 it ispossible to transfer the glow discharge from the cathode 40 to thecathode 41 by applying a negative pulse of relatively low amplitude andshort duration to the terminal 23 or positive pulse to terminal 22 ascompared to the amplitude and duration of the negative pulse which mustbe applied to the terminal 22 or positive pulse to terminal 23 totransfer the glow discharge from the cathode 41 to the cathode 40. As anexample, it has been found that for one given condition of operation anegative pip or spike pulse is suflicient to elfect glow transfer whenapplied to the terminal 23 as compared to a square pulse ofapproximately 100 microseconds duration which rnust be applied to theterminal 22 to insure reliable glow transfer. For equal ignitioncharacteristics at starting or equal cathode spacing relative to theanode, the glow discharge to a desired cathode can be accomplished byapplying the cold or initial striking voltage to the cathode to which.it is desired to create a glow discharge. This may be done by allowingthat cathode to be more negative than the other cathode until ionizationensues.

Variations in the amplitude of the pulses applied to the terminals 22and 23 may be obtained by varying the dis tance of the cathodes 40 and41 from the anode 33. For example, if cathode 46 is sufficiently moredistant from the anode 33 than the cathode 41 the pulse applied to theterminal 22 willhave to be of greater amplitude than that applied to theterminal 23. In this case the discharge will initiate between cathode 41and anode 33provided the cold striking voltage is less than thatrequired to create a glow discharge across 40-33. The size of the holein anode 33 or the amount of ionic coupling permitted is dependent uponthe spacing of the cathodes from the anode, the area of the anode andthe area of the cathodes, and the mixture and pressure of the gaseousatmosphere employed. As in the previously described'embodiments it isdesirable to permit suflicient ionic leakage into the unfired gap regionto facilitate rapid glow transfer but not enough ionic leakage to causeinstability. In other words, conditions illustrated by curve C (Fig. 2)are most desirable.

Voltage amplification may be effected by employing resistors 13 and 14of different values. For example, suppose resistor 13 i of larger valuethan resistor 14 and the voltage drop between anode 33 and cathode 41 isless than that between anode 33 and cathode 40. Then, when the glowdischarge is transferred from the cathode 40 to the cathode 41 there isno increase in the current through anode resistor 15 and a gain involtage amplification is accordingly effected.

Referring to Fig. 5a the embodiment i of particular utility when used asa binary sealer; i. e., input pulses are applied to terminal 24 and anoutput is derived from either of the terminals 22 or 23. Resistor 15 ischosen so that it will sustain a glow discharge to only one of thecathode 40 or 41 and resistor 13 is larger than resistor 14. Condensers43 and 44 in parallel with oath ode resistors 13 and 14, respectively,are provided to increase the stability of the glow transfer. Althoughthe value of resistor 15 is too large to permit glow present to both thecathodes 4t) and 41 simultaneously the resistor 13 has a larger valuethan the resistor 14 and the tendency to prevent the existence of glowdischarge between anode 33 and cathode 40 by the shorting out effectabove referred to is accordingly decreased because the voltage dropacross resistor 15 is substantially constant whether the glow dischargebe to the cathode 40 or to the cathode 41. The condensers 43 and 44ensure that the voltage between each cathode and the anode will besufliciently high to prevent a spurious glow transfer whilede-ionization is effected in the gap from which the glow discharge hasjust been transferred. If the impedance of 13 and 43 equals theimpedance of 14 and ,44 and condenser dis charge time is matched torepetition rate and width of pulses at 24 such as ensured.

Referring to Fig. 6, the novel switch-trigger tube 46 is shown incross-section and includes a starter anode SA] in spaced glow dischargerelation to a disc-shaped cathode C-1, having a hole through its center.This cathode C-l effectively divides the tube envelope into two ionization chambers linked together by the ionic leakage effected through thehole at the center of cathode 0-1. The starter anode SA-1 is situated inthe first or left-hand ionic chamber and the main anode MA, starteranode SA-2, and main cathode MC are situated in the second or right-handionic chamber. The main anode MA is of the wire type, starter anode SA-2is of the cylindrical wire mesh type and is positioned intermediate themain anode MA and the annular-shaped main cathode MC.

The enumerated electrodes are connected as shown and a positive inputpulse is applied to the input ter minals 48 and 50 in turn to effectoperation of the tube. That is a pulse must first be applied to theinput terminal 48 and subsequently a pulse must be applied to inputterminal 50 to derive an output from the output terminal 52 connected tothe main anode MA. Because of this required sequence of input pulses thetube 46 is termed a switch-trigger tube.

When an input pulse is applied to input terminal 48 and hence to thestarter anode SA-1 the voltage difierence between the anode SA-l and thecathode C1 is increased sufficiently to initiate a glow dischargetherebetween. This glow discharge is referred to as an auxiliary glowdischarge. Ions. and electrons then migrate through the hole in thecathode C-1 into the right-hand ionization chamber and thereby cause adecrease of the breakdown voltage required to effect a glow dischargetherein. While a glow discharge exists between the anode SA-l andcathode C1 an input pulse is applied to the input terminal 50. Thisinput pulse creates a sufficient voltage difference between the starteranode SA-2 and the main cathode MC to create a glow dischargetherebetween. This glow discharge between anode SA-2 and cathode MCeffects a further ionization of the gaseous atmosphere within theright-hand chamber. Thi ionization is sufiicient to cause the glowdischarge to be extended from the starter anode SA-Z to the morepositive main anode MA and thereby exist between the main cathode MC andthe main anode MA. This glow discharge is referred to as a main glowdischarge. In other words, the glow discharge between the main cathodeMC and the starter anode SA-2 provides the transfer current to initiatethe glow discharge between the main cathode MC and the main anode MA.When the input pulse applied to input terminal 48 ceases or the voltageacross the glow discharge between the starter anode SA-l and cathode C-1is caused to decrease below the required sustaining voltage such as byremoval of the B+ voltage source that glow discharge is extinguished.Also, when the input pulse applied to input terminal 50 ceases the glowdischarge between the main cathode MC and the starter anode SA-2 isextinguished. The glow discharges between the starter anode SA-l and thecathode C-1 and between SA2 and MC may be extinguished at any desiredtime after a glow discharge is created between MA and MC in theright-hand chamber without etfecting the operation of the tube. Anegative output voltage pulse appears at the output terminal 52 while aglow discharge is present between the main cathode MC and the main anodeMA.

The various electrodes are so positioned that the application of aninput pulse to either of the input terminals 48 and 50 alone will notproduce an output pulse or create a glow discharge in the right-handchamber. An output is produced only when an input pulse is applied tothe input terminal 48 to produce a glow discharge between the starteranode SA-1 and the cathode -1 and while that glow discharge exists aninput pulse is applied to the input terminal 50.

While there have been shown and described and pointed out thefundamental novel features of the invention as applied to a preferredembodiment, it will be understood that various omissions andsubstitutions and changes in the form and details of the deviceillustrated and in its operation may be made by those skilled in theart, without departing from the spirit of the invention. It is theintention, therefore, to be limited only as indicated by the scope ofthe following claims.

What is claimed is:

l. In a trigger tube of the glow transfer type, a single anode providinga preselected ionic leakage path therethrough, two cathodes unequallyspaced from and positioned on opposite sides of said anode; loadimpedances of different ohmic value connected in circuit with eachcathode so that the voltage drop across a glow discharge between theanode and that cathode having the higher ohmic impedance value incircuit therewith is less than the voltage drop across a glow dischargebetween the anode and the cathode having the lower ohmic value incircuit therewith; and a load resistor connected between the anode and asource of voltage, said load resistor being of such ohmic value that aglow discharge exists between the anode and only one of said cathodes atany given time, whereby voltage amplification is obtained when a glowdischarge is transferred from the cathode having the lower ohmicimpedance in circuit therewith to the cathode having the higher ohmicimpedance in circuit therewith.

2. A trigger tube of the glow transfer type having input and outputterminals; two cathode electrodes Within said tube; a single anodeelectrode intermediate said cathodes, said anode providing an ionicleakage path of predetermined limited area from the vicinity of eachcathode to the vicinity of the other; circuit means including individualimpedances coupled to said electrodes for rendering said tube operativeto establish a glow discharge between said anode and one of saidcathodes; said cathodes being of different physical size, havingdiiferent glow characteristics and being unequally spaced from saidanode so that the voltage drop across said glow discharge is differentwhen it exists to each of said cathodes; and means including at leastone of said terminals for receiving a pulse input to effect a transferof said glow discharge to a position between said anode and the other ofsaid cathodes.

References Cited in the file of this patent UNITED STATES PATENTS1,420,824 Donle June 27, 1922 1,919,263 Smith July 25, 1933 1,951,416Hund Mar. 20, 1934 1,992,493 Los Feb. 26, 1.935 2,575,516 Hagen Nov. 20,1951 2,638,564 Williams et al May 12, 1953

